class Solution {
public:
    int uniquePathsWithObstacles(vector<vector<int>>& obstacleGrid) {
        int m = obstacleGrid.size(), n = obstacleGrid[0].size();
        vector<vector<int>> dp(m + 1, vector<int>(n + 1, 0));
        for (int i = 0; i < m + 1; i++) dp[i][0] = 0;
        for (int j = 0; j < n + 1; j++) dp[0][j] = 0;
        dp[0][1] = 1;

        for (int i = 1; i < m + 1; i++)
        {
            for (int j = 1; j < n + 1; j++)
            {
                if (obstacleGrid[i - 1][j - 1] != 1)
                    dp[i][j] = dp[i - 1][j] + dp[i][j - 1];
                else dp[i][j] = 0;
            }
        }

        return dp[m][n];

    }
};